Ujjayini meridian
Also called: Ujjain meridian, Madhya rekha · Topic: Latitude, Longitude and Time · NCERT: Class 6, Ch 1 "Locating Places on the Earth"
Meaning
The Ujjayini meridian was the prime meridian of ancient Indian astronomy. It was called the madhya rekhā, meaning "middle line". It passed through Ujjayinī (Ujjain), a major centre of astronomy where Varāhamihira worked about 1,500 years ago. Indian astronomers used it as their zero line when working out longitude and time. It shows that India had a reference meridian long before Greenwich.
Example
Ujjain is in Madhya Pradesh. Old texts placed some other cities on this line, but they actually lie a little off it, because timekeeping was less exact then.
Don't confuse with
- Greenwich Prime Meridian: this is the modern 0° line through the Royal Observatory near London. It was adopted by international agreement in 1884.
- IST meridian (82°30′E): this sets India's standard time today. It passes near Mirzapur, not through Ujjain.